T-stat question - ZR-1 Net Registry Forums

tomtom72 · 01-20-2006

Hi Guys, I finally got the correct 1825-M spec coolant from GM so I'm going to get rid of the stuff the dealer put in my car. I figure on replacing the thermostat as I don't know how old it is.

My Q is if you are using a stock EPROM is a 180 stat worth getting? I'm not trying to be funny. It's just that the programing in the prom turns the fans on and off at some fairly hi temps. Will that programing work against the 180 stat? Will the 180 help in traffic or am I mis-informed??

I cleaned out my rad & condensor & oil cooler and installed a screen to stop stuff from getting back up in the cooling fins. I know I have a GM stat, 195*, in the system now. The cooling system responds when both fans are turned on and the temps come down. The temps are not a problem if the car is on the road but in slow traffic it gets up there and kind of stays at what looks like 200* more or less.

Thanks for any advice you want to share!

Tom

We Gone · 01-20-2006

I still have the stock t-stat but a custom chip that turns on both of the fans @ 205 off @ 200...

Steve

Bill · 01-20-2006

Make absolutely sure that it is the right style thermostat with the correct bypass valve. I got the wrong one and it cost me 2 radiators.

tomtom72 · 01-21-2006

Thanks to Steve and Bill!
Yes Bill I remember following the saga of the t-stat that was boxed wrong & caused you to loose the rad.! That stopped me at the time from scratching where it didn't itch! I had my local dealer do a flush & refil on my car back in Nov.05 and they used the wrong coolant so I figure if I use the the correct coolant I'm gonna open the t-stat housing to flush it with the motor runing. Having said that I fugured I should swap out the t-stat since I don't know how old it is, and that I'll be there anyway.

Steve, I get caught in traffic a good bit on some cruises and some cruises we go into NYC so I was looking for an edge on the engine temps. I can live with the stock T-stat as even though the coolant temp gets up there the oil temp stays below 1/2 way on the gauge even if I get caught for awhile in B to B stuff. Both come right down once airflow is re-established, man I'm so glad I clean that stuff & put the screen in!

Maybe I'll get a stocker and a NAPA 180 and do my own road test!
Thanks for the input guys!

Tom

Tom · 01-23-2006

The temperature gauges are very non-linear. The 90 only had values at the end point while later cars had additional divisions and values. The mid-point of the needle travel on your 90 does not equal halfway between the 100 and 260 values on the gauge. The mid-point on the oil temperature gauge equals 220 deg and the mid-point on the water temperature gauge equals 210 deg. "The Legend" magazine from the ZR-1 registry had an article that included a table and diagram showing the actual values. I copied the table/diagram and keep a copy in my console as a reference. I have seen the same table on the internet but I don't remember where, I thought it was on this site but I couldn't find it recently.

tomtom72 · 01-24-2006

Tom how did you know that I was thinking about that? Thanks man!

Doing the math it didn't make sense to me that the gauge reading had a linear progression! It just seemed too low of a temp reading, by the math that is. I guess it's worth a try with a 180 just to see if in traffic I get a lower overall coolant temp...even a little would make me feel better. I feel so much better when I see the needle 1/2 way instead of 3/4 or more up the gauge face! It only happens in traffic without the climate control "on", if I use the CC the other fan kicks in and brings the temp down a bit. I think it's a perception thing with me...I hate to see a temp gauge up so high in traffic and my first instinct is to turn off the CC. My 72 LT-1 A/C coupe would never allow me to stay in B to B traffic with the A/C on! Guess I gotta get used to this new hi-tech corvette.

thank you for the info!

2nd94Z · 11-06-2006

Hello all, my (new to me) 94 on the freeway at 70 gets to 209 in 60 weather, seems a little warm, after leaving the freeway it goes back to 195 or 200, think I need a new thermo ? and whats the number or brand from the parts store ?

jonszr1 · 11-06-2006

I had the same temp readings in one of my 90s. Not soon there after my head gasket let loose. I think it was leaking causing the temp to go up . I'm not sure if your issue was the sam.e as mine. I just wanted to share what happened to me so you can keep an eye out. hope this helps

Hammer · 11-06-2006

OK guys, from what I have learned from the Gathering and various other sites, this is the picture of the t-stat you need. MAKE SURE THE ONE YOU GET IS EXACTLY LIKE THIS ONE. Look closely at the top and the bottom. The wrong stat has a pointed top and a cone or bucket shaped bottom. Make sure you drain the system entirely and use ONLY distilled water and GREEN antifreeze when refilling. Hope this helps.

01-20-2006	#1
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	T-stat question Hi Guys, I finally got the correct 1825-M spec coolant from GM so I'm going to get rid of the stuff the dealer put in my car. I figure on replacing the thermostat as I don't know how old it is. My Q is if you are using a stock EPROM is a 180 stat worth getting? I'm not trying to be funny. It's just that the programing in the prom turns the fans on and off at some fairly hi temps. Will that programing work against the 180 stat? Will the 180 help in traffic or am I mis-informed?? I cleaned out my rad & condensor & oil cooler and installed a screen to stop stuff from getting back up in the cooling fins. I know I have a GM stat, 195, in the system now. The cooling system responds when both fans are turned on and the temps come down. The temps are not a problem if the car is on the road but in slow traffic it gets up there and kind of stays at what looks like 200 more or less. Thanks for any advice you want to share! Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

01-20-2006	#2
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,170	Re: T-stat question I still have the stock t-stat but a custom chip that turns on both of the fans @ 205 off @ 200... Steve

01-20-2006	#3
Bill Join Date: Mar 2004 Location: Sacramento, CA. Posts: 141	Re: T-stat question Make absolutely sure that it is the right style thermostat with the correct bypass valve. I got the wrong one and it cost me 2 radiators. __________________ [img]http://home.comcast.net/%7Ebsoomann/srsig.jpg[/img]

01-21-2006	#4
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: T-stat question Thanks to Steve and Bill! Yes Bill I remember following the saga of the t-stat that was boxed wrong & caused you to loose the rad.! That stopped me at the time from scratching where it didn't itch! I had my local dealer do a flush & refil on my car back in Nov.05 and they used the wrong coolant so I figure if I use the the correct coolant I'm gonna open the t-stat housing to flush it with the motor runing. Having said that I fugured I should swap out the t-stat since I don't know how old it is, and that I'll be there anyway. Steve, I get caught in traffic a good bit on some cruises and some cruises we go into NYC so I was looking for an edge on the engine temps. I can live with the stock T-stat as even though the coolant temp gets up there the oil temp stays below 1/2 way on the gauge even if I get caught for awhile in B to B stuff. Both come right down once airflow is re-established, man I'm so glad I clean that stuff & put the screen in! Maybe I'll get a stocker and a NAPA 180 and do my own road test! Thanks for the input guys! Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

01-23-2006	#5
Tom Join Date: Jan 2004 Location: Southern CA Posts: 108	Re: T-stat question The temperature gauges are very non-linear. The 90 only had values at the end point while later cars had additional divisions and values. The mid-point of the needle travel on your 90 does not equal halfway between the 100 and 260 values on the gauge. The mid-point on the oil temperature gauge equals 220 deg and the mid-point on the water temperature gauge equals 210 deg. "The Legend" magazine from the ZR-1 registry had an article that included a table and diagram showing the actual values. I copied the table/diagram and keep a copy in my console as a reference. I have seen the same table on the internet but I don't remember where, I thought it was on this site but I couldn't find it recently.

01-24-2006	#6
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: T-stat question Tom how did you know that I was thinking about that? Thanks man! Doing the math it didn't make sense to me that the gauge reading had a linear progression! It just seemed too low of a temp reading, by the math that is. I guess it's worth a try with a 180 just to see if in traffic I get a lower overall coolant temp...even a little would make me feel better. I feel so much better when I see the needle 1/2 way instead of 3/4 or more up the gauge face! It only happens in traffic without the climate control "on", if I use the CC the other fan kicks in and brings the temp down a bit. I think it's a perception thing with me...I hate to see a temp gauge up so high in traffic and my first instinct is to turn off the CC. My 72 LT-1 A/C coupe would never allow me to stay in B to B traffic with the A/C on! Guess I gotta get used to this new hi-tech corvette. thank you for the info! __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

11-06-2006	#7
2nd94Z Join Date: Sep 2006 Location: Little Rock, Arkansas Posts: 35	Re: T-stat question Hello all, my (new to me) 94 on the freeway at 70 gets to 209 in 60 weather, seems a little warm, after leaving the freeway it goes back to 195 or 200, think I need a new thermo ? and whats the number or brand from the parts store ?

11-06-2006	#8
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: T-stat question I had the same temp readings in one of my 90s. Not soon there after my head gasket let loose. I think it was leaking causing the temp to go up . I'm not sure if your issue was the sam.e as mine. I just wanted to share what happened to me so you can keep an eye out. hope this helps

11-06-2006	#9
Hammer Join Date: Apr 2006 Location: Ideho Posts: 2,653	Re: T-stat question OK guys, from what I have learned from the Gathering and various other sites, this is the picture of the t-stat you need. MAKE SURE THE ONE YOU GET IS EXACTLY LIKE THIS ONE. Look closely at the top and the bottom. The wrong stat has a pointed top and a cone or bucket shaped bottom. Make sure you drain the system entirely and use ONLY distilled water and GREEN antifreeze when refilling. Hope this helps. __________________ [I][FONT=Comic Sans MS]John Boyd[/FONT][/I] [I][FONT=Comic Sans MS][SIZE=1]Ideho[/SIZE][/FONT][/I] [FONT=Comic Sans MS][SIZE=1][I]2015 ZL1 [/I][I]Camaro #1121 BLACK/BLACK 6 SPD (540 RWHP)[/I][/SIZE][/FONT] [I][FONT=Comic Sans MS][SIZE=1]1991 ZR-1 #458 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK 72[/COLOR]k miles ([B][COLOR=red]SOLD[/COLOR][/B]) 1991 ZR-1 #473 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK [/COLOR]37k miles ([B][COLOR=red]SOLD[/COLOR][/B])[/SIZE][/FONT][/I] Last edited by Hammer; 02-05-2007 at 10:40 AM.

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